specs2 - lamdbajam 2014

Epic Success V Failure ? Refactoring to real FP

Eric Torreborre

Why, oh why?

What now?

How hard can it be?

HelloWorldSpec.scala

How hard can it be?

TextText

ExampleExample

TextText

TextText

ExampleExample

StepStep

ExampleExample

Filterin

gFilterin

gby

nameby

nameby

previousby

previous

Executio

nExecutio

nconcurre

ntconcurre

ntcondition

alcondition

al

ReportingReporting

consoleconsole

htmlhtml

How hard can it be?

Configuration(s)Configuration(s)ResourcesResources

FileSystemFileSystem

“Flow”“Flow”

StateState

CompositionComposition

ErrorsErrors

Problem?

Strategy

Strategy

Filtering by name

Filtering by previous

TextText ExampleExample ExampleExample TextText

StatsStats

resultresult

resultresultresultresult

resultresultresultresult

Monad stacks

Task[A]Task[A]

AA

ErrorError

AA

ErrorError

AA

FutureFuture

Monad stacks values

AAErrorError

FutureFuture

now(a: A)

delay(a: =>A)AA

ErrorError

FutureFuture

AAErrorError

FutureFuture

fail(t: Throwable)

and

flatM

ap!

and

flatM

ap!

Action in action

Action[A]Action[A]

AA

ErrorError

AA

ErrorError

AA

IOIO

AA

ErrorError

IOIO

ReaderReader

Conf => IO[A] => IO[Error]

Error = String | Throwable | (String, Throwable)

Action in action

Action opportunity

Read

everything

!

Read

everything

!

Filtering by previous

TextText ExampleExample ExampleExample TextText

StatsStats

resultresult

resultresultresultresult

resultresultresultresult

Filtering by previous

TextText ExampleExample ExampleExample TextText

StatsStats

resultresult

Action[Fragment] => Task[Fragment]

Fragment => Action[Result]

Action[Result] => Action[Fragment]

mapmap

Task[Fragment] => Process[Task, Fragment]

evaleval

Filtering by previous

flatM

ap!

flatM

ap!

Filtering by previous

On stacks

No big

dealNo big

deal

SpecialiseSpecialise

LibraryLibrary

Composition?Composition?

Integration?Integration?

Scalaz-stream

Concurrency with

Easy!Easy!

Concurrency with

With

state!With

state!

TextText ExampleExample ExampleExample StepStep ExampleExample

stop herestop here

Flatmap with

Online

testing!Online

testing!

Flatmap with

Online

testing!Online

testing!

Text1Text1 Example1Example1 Example2Example2 Example3Example3

Text1Text1 Example1Example1 Example2Example2 Example3Example3

Example2.1Example2.1 Example2.2Example2.2

Reporting with

“duplicate”stream

“duplicate”stream

Write to consoleWrite to console

Accumulatestate

Accumulatestate

Reporting with

Text1Text1 Example1Example1 Example2Example2 Example3Example3

“t1”“t1” “e1”“e1” “e2”“e2” “e3”“e3”

> Console

statsstats statsstats statsstats

Reporting with

Not composable

Not composable

Reporting with and Folds!

Reporting with and Folds!

Reporting with and Folds!

Opaque

dependent

type

Opaque

dependent

type

Reporting with and Folds!

Fold Monoid!Fold Monoid!

Reporting with and Folds!

Conclusion